Is semantic verbal fluency impairment explained by executive function deficits in schizophrenia?

The associations of negative and disorganization symptoms with verbal fluency in schizophrenia: the mediation effect of processing speed and cognitive flexibility

BACKGROUND

Psychopathological symptoms appear important for cognitive functions in schizophrenia. Nevertheless, the factors and their impact on relationships between negative or disorganization symptoms and verbal fluency are still debatable. The preliminary objective of the study was to compare verbal fluency, including clustering and switching as cognitive strategies, executive functions, and processing speed between individuals with schizophrenia (SZ) and healthy controls (HC). The main aim of the study was to investigate mediation models and identify whether relationships between negative and disorganization symptoms and verbal fluency in schizophrenia are mediated by cognitive flexibility and processing speed.

METHODS

Semantic (animal and fruit) and phonemic (letter k and letter f) fluency tasks, the Berg Card Sorting Test (BCST), and the Color Trails Test (CTT) were administered in the SZ group (n = 108) and a matched HC group (n = 108). The Positive and Negative Syndrome Scale (PANSS) was applied to measure psychopathological symptoms in schizophrenia patients.

RESULTS

SZ produced fewer words, had larger cluster size, and fewer switches in semantic fluency than HC. Moreover, the SZ group had longer completion time in CTT 1 and CTT 2 and higher percent of perseverative and non-perseverative errors in BCST than HC. Three mediation models demonstrated good fit indices, suggesting that processing speed and cognitive flexibility were significant mediators for relationships between: (1) psychopathological symptoms and productivity or semantic clustering in animal fluency; (2) negative symptoms and productivity in semantic or phonemic fluency; and (3) disorganization symptoms and productivity in semantic fluency.

CONCLUSIONS

Individuals with schizophrenia are characterized by a specific performance profile on verbal fluency tasks. They manifest poor productivity and problems using cognitive strategies for semantic fluency. Referring to executive functioning, schizophrenia patients exhibit decreased cognitive flexibility, problem-solving, and formulating concepts, as well as slow processing speed. It was found that processing speed and cognitive flexibility may be understood as the neuropsychological mechanisms modifying the relationships between negative symptoms, disorganization symptoms, and semantic and phonemic fluency. Therefore, these results provide a foundation for including cognitive flexibility and processing speed in cognitive remediation for schizophrenia patients.

Formal Thought Disorders and Neurocognition in Treatment-Resistant Schizophrenia: Trouble du cours de la pensée et neurocognition dans la schizophrénie réfractaire

OBJECTIVE

Formal thought disorders (FTDs), a core feature of schizophrenia, have been subdivided into positive and negative types, and are clinically assessed by examining speech (objective) or patient introspection (subjective). Despite being associated with poorer treatment response and worse outcomes, FTDs have been understudied in patients with schizophrenia, in particular treatment-resistant schizophrenia (TRS) or schizoaffective disorder. We aimed to explore the relationship between the severity of positive and negative FTDs and neurocognition as well as social/occupational functioning in this clinical subgroup.

METHOD

This was a retrospective chart review conducted at the Clozapine Clinic at the Centre for Addiction and Mental Health, Toronto, Canada. We reviewed charted standardized assessment of FTDs using the Thought and Language Disorder (TALD) scale, neurocognition using the Brief Cognitive Assessment Tool for Schizophrenia (B-CATS), and functioning using the Social and Occupational Functioning Assessment Scale (SOFAS) between October 2022 and June 2023. Following the original factor structure of the TALD, we computed 4- factor scores that combined positive or negative and objective or subjective FTDs. We then explored the correlation between the scores from each TALD factor and the neurocognition and functioning scores.

RESULTS

We analysed data for 23 outpatients on clozapine. After the Bonferroni adjustment, total TALD scores, indicating overall severity of FTDs, were strongly and inversely correlated with SOFAS scores (p < 0.001). A strong inverse correlation was found between the objective positive TALD factor and Letter-Number Span verbal working memory scores, r(21) = -0.63, p < 0.001.

CONCLUSIONS

Our results demonstrate the strong relationship between FTDs, neurocognition, and social/occupational functioning in a sample of TRS outpatients. Within the cognitive domains assessed, verbal working memory impairment had the strongest correlation with positive FTDs, such as derailment or tangentiality. These findings highlight the value of employing standardized psychopathological scales for FTDs in clinical practice.

The Category Fluency Test components and their association with cognition and symptoms in adolescents with schizophrenia

Background

The category Fluency Test (CFT) is included in the MATRICS consensus cognitive battery for schizophrenia (MCCB). This test has several components that allow the exploration of other cognitive functions and could be related to different symptom profiles.

Methods

a sample of 98 Mexican adolescents was evaluated with the CFT and the following components were analyzed: total words, errors, clusters, switching, related words, and categories. Demographic and clinical differences among them and correlations with other MCCB tests and with Positive and Negative Syndrome Scale (PANSS) factors were explored.

Results

The CFT components showed significant correlations with each other and with other MCCB tests, particularly with those related to verbal learning, working memory, and speed of processing. In addition, they showed moderate correlations with the total PANSS score and with the negative, positive, and cognitive PANSS factors.

Conclusions

The analysis of CFT components allows clinicians and investigators to obtain information regarding other cognitive functions and symptom profiles in adolescents with schizophrenia.

Executive control of language in schizophrenia patients with history of auditory verbal hallucinations: A neuropsychological and resting-state fMRI study

BACKGROUND

As demonstrated by a plethora of studies, compromised executive functions (EF) and language are implicated in mechanisms of auditory verbal hallucinations (AVH), but the contribution of their interaction to AVH remains unclear. We hypothesized that schizophrenia patients with history of AVH (AVHh+) vs. without history of AVH (AVHh-) have a specific deficit of executive control of language and alterations in functional connectivity (FC) between the brain regions involved in EF and language, and these neuropsychological and neurophysiological traits are associated with each other.

METHODS

To explore the executive control of language and its contribution to AVH, we used an integrative approach involving analysis of neuropsychological and resting-state fMRI data of 34 AVHh+, 16 AVHh-, and 40 healthy controls. We identified the neuropsychological and FC measures that differentiated between AVHh+, AVHh-, and HC, and tested the associations between them.

RESULTS

AVHh+ were characterized by decreased category and phonological verbal fluency, utterance length, productivity in the planning tasks, and poorer retelling. AVHh+ had decreased FC between the left inferior frontal gyrus and the anterior cingulate cortex. Productivity in category verbal fluency was associated with the FC between these regions.

CONCLUSIONS

Poor executive control of word retrieval and deficient programming of sentence and narrative related to more general deficits of planning may be the neuropsychological traits specific for AVHh+. A neurophysiological trait specific for AVHh+ may be a decreased FC between regions involved in language production and differentiation between alien- vs. self-generated speech and between language production vs. comprehension.

Linguistic findings in persons with schizophrenia-a review of the current literature

INTRODUCTION

Alterations of verbalized thought occur frequently in psychotic disorders. We characterize linguistic findings in individuals with schizophrenia based on the current literature, including findings relevant for differential and early diagnosis.

METHODS

Review of literature published via PubMed search between January 2010 and May 2022.

RESULTS

A total of 143 articles were included. In persons with schizophrenia, language-related alterations can occur at all linguistic levels. Differentiating from findings in persons with affective disorders, typical symptoms in those with schizophrenia mainly include so-called "poverty of speech," reduced word and sentence production, impaired processing of complex syntax, pragmatic language deficits as well as reduced semantic verbal fluency. At the at-risk state, "poverty of content," pragmatic difficulties and reduced verbal fluency could be of predictive value.

DISCUSSION

The current results support multilevel alterations of the language system in persons with schizophrenia. Creative expressions of psychotic experiences are frequently found but are not in the focus of this review. Clinical examinations of linguistic alterations can support differential diagnostics and early detection. Computational methods (Natural Language Processing) may improve the precision of corresponding diagnostics. The relations between language-related and other symptoms can improve diagnostics.

Atypical frontotemporal cortical activity in first-episode adolescent-onset schizophrenia during verbal fluency task: A functional near-infrared spectroscopy study

Background

Frontotemporal cortex dysfunction has been found to be associated with cognitive impairment in patients with schizophrenia (SCZ). In patients with adolescent-onset SCZ, a more serious type of SCZ with poorer functional outcome, cognitive impairment appeared to occur at an early stage of the disease. However, the characteristics of frontotemporal cortex involvement in adolescent patients with cognitive impairment are still unclear. In the present study, we aimed to illustrate the frontotemporal hemodynamic response during a cognitive task in adolescents with first-episode SCZ.

Methods

Adolescents with first-episode SCZ who were aged 12-17 and demographically matched healthy controls (HCs) were recruited. We used a 48-channel functional near-infrared spectroscopy (fNIRS) system to record the concentration of oxygenated hemoglobin (oxy-Hb) in the participants' frontotemporal area during a verbal fluency task (VFT) and analyzed its correlation with clinical characteristics.

Results

Data from 36 adolescents with SCZ and 38 HCs were included in the analyses. Significant differences were found between patients with SCZ and HCs in 24 channels, mainly covering the dorsolateral prefrontal cortex, superior and middle temporal gyrus and frontopolar area. Adolescents with SCZ showed no increase of oxy-Hb concentration in most channels, while the VFT performance was comparable between the two groups. In SCZ, the intensity of activation was not associated with the severity of symptoms. Finally, receiver operating characteristic analysis indicated that the changes in oxy-Hb concentration could help distinguish the two groups.

Conclusion

Adolescents with first-episode SCZ showed atypical cortical activity in the frontotemporal area during the VFT, and fNIRS features might be more sensitive indicators in cognitive assessment, indicating that the characteristic hemodynamic response pattern might be potential imaging biomarkers for this population.

Mimicking effects of auditory verbal hallucinations on language production at the level of words, sentences and stories

Schizophrenia is characterised foremost by hallucinations, delusions and disorganised speech. Deficits in the internal speech monitor may contribute to the development of auditory-verbal hallucinations. This study investigates potential effects in the opposite direction: could the presence of auditory-verbal hallucinations have an effect on speech production? To this end, a recent mimicking/simulation approach was adopted for 40 healthy participants who perceived either white noise or hallucination-like speech recordings during different language production tasks with increasing demands: picture naming, verbal fluency with and without category switch, sentence production, and discourse. In line with reports about real schizophrenia cases in the literature, mimicking auditory-verbal hallucinations affected verbal fluency (switch condition) and sentence production (duration) in a different way than mere noise. These effects were not correlated, suggesting that hallucinations may even affect different levels of linguistic complexity in different ways. Anyway, in both cases (mimicked), auditory hallucination appear to contribute to the emergence of disordered speech. The mimicking/simulation paradigm may in future help to identify and disentangle the various factors contributing to disorganised speech in schizophrenia. They may also support the development and implementation of new protocols, e.g., in speech and language therapy in persons with schizophrenia in order to improve their communication skills despite the presence of auditory-verbal hallucinations.

Disembodied Language in Early-Onset Schizophrenia

A recent view on schizophrenia phenomenology underlines the impaired relations between the mind and the body. An aberrant feeling of ipseity may be the real source of suffering of the patients from psychosis and impacts general symptomatology. The disturbed connection between thinking processes and environmental stimuli may lead to language disembodiment. In the study, we aimed to experimentally test the presence of disembodied language and investigate its association with symptoms of psychosis in adolescents diagnosed with early-onset schizophrenia spectrum disorders. Assessment of language embodiment was conducted using the Zabór Verbal Task (ZVT) with concurrent linguistic and clinical assessment using the Thought, Language, and Communication Scale (TLCS) and Positive and Negative Symptoms Scale (PANSS). The study group of patients (n = 31) aged 11-18 years, with the diagnosis of schizophrenia spectrum according to Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) and the International Classification of Diseases (ICD-10) criteria, was compared with a sex- and age-matched healthy control sample (n = 31). Patients with psychosis made more errors in ZVT than healthy controls (p = 0.01) and this parameter did not improve after 6-8 weeks of standard treatment (p = 0.55). A higher number of errors in ZVT were associated with the presence of auditory hallucinations (odds ratio [OR] 1.14; 95% CI 1.02-1.26). ZVT errors coincided with perception disorders, alternatively to the TLCS scores where we observed association with abnormal beliefs. The results of these preliminary studies indicate the value of the phenomenological approach in the diagnosis of schizophrenia spectrum and suggest a potential involvement of language disembodiment in symptomatology.

High-Order Language Processing Difficulties in Patients With Schizophrenia: Cross-linguistic and Cross-cultural Results From the Hindi Version of a Newly Developed Language Test

Objective

To detect subtle linguistic performance deficits in patients with schizophrenia, a test battery was developed in Hindi vernacular language.

Method

It was a replication study of observational, analytical, and case-control design. Total of 86 participants, namely 43 patients with schizophrenia and 43 controls, were recruited into the study. The patients were evaluated by using PANSS (positive and negative symptoms scale for schizophrenia) for recruitment into the study. Participants from the general population were evaluated with GHQ-12 (General Health Questionnaire-12) to be found to fit as healthy controls. Subsequently, the linguistic performance of patients (on HLFT: Hindi linguistic function test) was compared with that of controls. The HLFT battery was designed, containing 3 blocks by using antonyms, synonyms, homonyms, hyperonyms, hyponyms, distractors, and adages.

Result

Patients scored significantly less than that of controls in identifying antonyms, distractors, and hyponyms while in identifying homonyms they scored significantly more than that of controls. At block I (antonyms) score of 15.5; at homonym score of 5.5; at hyponym (as in hyponym plus distractor combination) score of 2.5, the sensitivity and specificity for using them as a cutoff to screen for schizophrenia are 60.5% and 67.4%; 86% and 41.9%; 81.4% and 46.5%, respectively.

Conclusion

Ambiguity processing of taxonomic representation such as antonymia, homonymia, hypo-/hyperonymia, synonymia, and also understanding of adages might be significantly impaired in patients with schizophrenia. The HLFT battery could be used as a quick and sensitive instrument to detect and quantify the linguistic difficulties of patients with schizophrenia.

Executive Functions Influence on Memory Process in Patients with Paranoid Schizophrenia and Bipolar Disorders with and without Psychotic Symptoms. A Pilot Study

The objective of the present study was to evaluate whether declarative memory deficits are related to executive function deficits (EF), since they could be a consequence of a poor organization of the material to memorize. This interaction between both cognitive processes can be studied simultaneously in a single task such as the Test of Memory Strategies (TSM). 23 patients with paranoid schizophrenic disorder, 11 with bipolar disorder with psychotic symptoms, 13 with bipolar disorder without psychotic symptoms and 15 healthy subjects were evaluated with the TSM; with the memory test Texts A and B (subtest of the Barcelona neuropsychological assessment battery), which assesses short-term and immediate recall without the influence of EF; and with the Trail Making Test (TMT): Part A (sustained attention) and Part B (executive control). The patients groups and the control group showed an improvement in memory performance across each of the TSM conditions. However, this facilitating effect of the strategies differed among the groups (the patients with higher EF deficits showed less improvement). Regarding these results, we conclude that this cognitive process cannot be independent of EF. However, due to the pilot nature of this study, it would be recommended to replicate these findings in new studies.

Corrigendum to: Semantic Memory Impairment Across the Schizophrenia Continuum: A Meta-Analysis of Category Fluency Performance

[This corrects the article DOI: 10.1093/schizbullopen/sgaa054.].

Semantic Memory Impairment Across the Schizophrenia Continuum: A Meta-Analysis of Category Fluency Performance

Semantic memory (SM) impairments are a core feature of schizophrenia and are present along the psychosis continuum. It is, however, unclear whether the degree of SM impairments vary along this continuum and if demographic and clinical factors affect impairment severity. This study performed meta-analyses of category fluency task performance (a task commonly used to assess SM) in 4 groups along the schizophrenia continuum: high schizotypes (HSZT), first-degree relatives (FDR), recent-onset patients (≤2 y; ROP) and chronic patients (CSZ). Electronic databases were searched for relevant studies published up to October 2019 resulting in the inclusion of 48 articles. The main analyses assessed fluency productivity scores in 2978 schizophrenia spectrum disorder patients, 340 first-degree relatives of schizophrenia spectrum disorder patients, and 3204 healthy controls. Further analyses assessed errors, mean cluster size, and switching data that were available in the CSZ group only. Results revealed significant impairments in fluency productivity were present in the FDR, ROP, and CSZ groups relative to healthy controls, but not in HSZT. In the CSZ group, significant differences relative to healthy controls were also observed in non-perseverative errors, mean cluster size, and number of switches. The findings collectively suggest that SM deficits are present at each stage of the continuum and are exacerbated post-illness onset. They also support the centrality of SM impairments in schizophrenia and most elevated risk groups. Future studies with more diverse measures of SM function are needed to replicate and extend this research.

Semantic Search in Psychosis: Modeling Local Exploitation and Global Exploration

Impairments in category verbal fluency task (VFT) performance have been widely documented in psychosis. These deficits may be due to disturbed “cognitive foraging” in semantic space, in terms of altered salience of cues that influence individuals to search locally within a subcategory of semantically related responses (“clustering”) or globally between subcategories (“switching”). To test this, we conducted a study in which individuals with schizophrenia (n = 21), schizotypal personality traits (n = 25), and healthy controls (n = 40) performed VFT with “animals” as the category. Distributional semantic model Word2Vec computed cosine-based similarities between words according to their statistical usage in a large text corpus. We then applied a validated foraging-based search model to these similarity values to obtain salience indices of frequency-based global search cues and similarity-based local cues. Analyses examined whether diagnosis predicted VFT performance, search strategies, cue salience, and the time taken to switch between vs search within clusters. Compared to control and schizotypal groups, individuals with schizophrenia produced fewer words, switched less, and exhibited higher global cue salience, indicating a selection of more common words when switching to new clusters. Global cue salience negatively associated with vocabulary ability in controls and processing speed in schizophrenia. Lastly, individuals with schizophrenia took a similar amount of time to switch to new clusters compared to control and schizotypal groups but took longer to transition between words within clusters. Findings of altered local exploitation and global exploration through semantic memory provide preliminary evidence of aberrant cognitive foraging in schizophrenia.

Altered selection during language processing in individuals at high risk for psychosis

INTRODUCTION

Performance in the executive function (EF) domain has been linked to symptoms and functional outcomes in psychosis. Studies have found that UHR populations have difficulty with verbal fluency, which involves multiple facets of EF. Two potentially implicated EF facets were examined to explore whether these could be dissociated in UHR populations: selection among alternatives (measured by selection costs) and retrieval from semantic memory retrieval (measured by retrieval costs).

METHODS

A total of 45 UHR individuals and 46 healthy controls (HVs) were assessed with a verb generation task. Differences in selection cost (RT difference between high and low selection demand conditions) and retrieval cost (RT difference between high and low retrieval demand conditions) were examined and participants were also assessed for clinical symptoms.

RESULTS

The UHR group showed greater selection costs relative to HVs, F (1, 91) = 4.39, p = 0.039. However, there were no group differences on retrieval cost, F (1, 91) = 0.63, p = 0.43. A positive association (r = 0.41) was found between disorganized and negative symptoms and selection costs (but not retrieval costs) in the UHR group. There was no significant association between selection costs and positive symptoms.

DISCUSSION

Increased selection costs may reflect impaired performance in the neural inhibition domain of EF in the UHR population, potentially underlying a mechanistically distinct EF subdomain that affects the group's ability to efficiently select between competing options. Findings suggest that UHR individuals may exhibit impairment in selecting among alternatives, but not in retrieval from semantic memory.

Component mechanisms of executive function in schizophrenia and their contribution to functional outcomes

OBJECTIVE

In schizophrenia, scores reflecting deficits in different cognitive processes are strongly correlated, making it difficult to establish a solid relationship between different cognitive mechanisms and other features of this disorder. The objective of this study was to explore whether three frequently postulated executive functions (updating, shifting, and inhibition) could be compared between groups and considered independently in terms of their respective roles in functional outcome.

METHODS

This study relied on confirmatory factor analysis of schizophrenia patients (n=141) and healthy controls (n=119). The main analyses examined the degree to which three executive functions (updating, set-shifting, and inhibition) could be separated in schizophrenia and compared this model among groups. Structural equation modeling analysis was also performed to examine the extent to which executive function components contribute to functional outcome in schizophrenia.

RESULTS

Multiple-group confirmatory factor analysis with unconstrained model parameters indicated that the full three-factor model may fit the data in both groups (χ2 = 61.48, degrees of freedom = 34, p < 0.001, comparative fit index = 0.95; standardized root mean square residual = 0.037; root mean square error of approximation = 0.04; Akaike's information criteria = 169.49; normed fit index = 0.90), although there was also a good data fit for the patient group with a two-factor model. In the patient group, structural equation modeling suggested that shifting and (principally) updating were associated with the general measure of functional outcome (regression path coefficients: 0.34, p < 0.005; 0.39, p < 0.005, respectively), although when combined the mechanisms fail to contribute.

CONCLUSION

This data suggests that the factor structure may be similar but not identical between groups, and both updating and shifting may play an important role in functional outcome in schizophrenia.

Motor and cognitive impairments in spinocerebellar ataxia type 7 and its correlations with cortical volumes

Spinocerebellar Ataxia Type 7 (SCA7) is a neurodegenerative disorder caused by cytosine-adenine-guanine (CAG) repeat expansion. It is clinically characterized by ataxia and visual loss. To date, little is known about SCA7 cognitive impairments and its relationship with grey matter volume (GMV) changes. The aim of this study was to explore SCA7 patients' performance in specific components of auditory-verbal neuropsychological tests and to correlate their scores with genetic mutation, severity of ataxia and GMV. We assessed verbal memory and verbal fluency proficiencies in 31 genetically confirmed SCA7 patients, and compared their results with 32 healthy matched volunteers; we also correlated CAG repeats and severity of motor symptoms with performance in the auditory-verbal tests. SCA7 patients exhibited deficiencies in several components of these cognitive tasks, which were independent of motor impairments and showed no relation to CAG repeats. Based on Resonance Images performed in 27 patients we found association between ataxia severity and GMV in "sensoriomotor" cerebellum, as well as correlations of impaired verbal memory and semantic fluency scores with GMV in association cortices, including the right parahippocampal gyrus. To our knowledge, this is the first report of deficits in the organization of semantic information and in the evocation of verbal material, as well as greater susceptibility to proactive interference in SCA7 patients. These findings bring novel information about specific cognitive abilities in SCA7 patients, particularly verbal memory and fluency, and their relation with GMV variations in circumscribed brain regions, including association cortices known to have functional relationships with the cerebellum.

Protocolo de evaluación de la prosodia emocional y la pragmática en personas con esquizofrenia

La esquizofrenia se caracteriza por una distorsión del pensamiento, las percepciones, las emociones, el lenguaje, la conciencia de sí mismo y la conducta. Afecta a más de 21 millones de personas en todo el mundo y es una de las 10 enfermedades más incapacitantes según la Organización Mundial de la Salud, pero existe escasa evidencia sobre el déficit lingüístico con el que cursa la enfermedad. Estudio transversal y cuasi-experimental donde se analizan los datos resultantes de la evaluación por medio de diferentes pruebas de las áreas de pragmática y prosodia en una muestra compuesta por 96 sujetos, de los cuales 48 (50%) no tienen enfermedad mental y componen el grupo control y 48 (50%) tienen enfermedad mental y componen el grupo experimental.De acuerdo con la clasificación de Crow (1978), el 56,7% de los sujetos del grupo experimental (27 sujetos) tiene sintomatología positiva y el 43,8% (21 sujetos) tiene sintomatología negativa. Se observan diferentes patrones de déficit según la sintomatología, así como una afectación de las áreas evaluadas en el estudio (pragmática y prosodia afectiva).La esquizofrenia cursa con déficit en las áreas analizadas, si bien existe una controversia acerca de su origen. En relación con la pragmática, encontramos interpretaciones literales en ambos tipos de pacientes, aunque son más frecuentes en los sujetos con sintomatología positiva. En cuanto a la prosodia, encontramos frecuencias fundamentales excesivas, monotonía en la expresión de las emociones y dificultades para comprender emociones a través de los aspectos prosódicos.

Eotaxin, an Endogenous Cognitive Deteriorating Chemokine (ECDC), Is a Major Contributor to Cognitive Decline in Normal People and to Executive, Memory, and Sustained Attention Deficits, Formal Thought Disorders, and Psychopathology in Schizophrenia Patients

Eotaxin is increased in neurodegenerative disorders and schizophrenia, and preclinical studies indicate that eotaxin may induce cognitive deficits. This study aims to examine whether peripheral levels of eotaxin impact cognitive functioning in healthy volunteers and formal thought disorder (FTD) and psychopathology in schizophrenia patients. Serum levels of eotaxin were assayed and cognitive tests were performed on a sample of 40 healthy participants and 80 schizophrenia patients. Among healthy participants, eotaxin levels were significantly associated with episodic/semantic memory, executive functions, Mini Mental State Examination, emotion recognition, and sustained attention. In addition, age-related effects on these cognitive measures were partly mediated by eotaxin. The super-variable "age-eotaxin" predicted a large part of the variance in cognitive functions among healthy participants, and hence, eotaxin may act as an "accelerated brain aging chemokine" (ABAC). In schizophrenia, eotaxin levels had a strong impact on formal thought disorders and psychopathology. In schizophrenia, increased eotaxin strongly impacts memory and sustained attention, which together to a large extent determine FTD. FTD together with memory deficits predicts around 92.5% of the variance in psychopathology. Moreover, the effects of eotaxin are partially mediated by executive functioning, while the effects of male sex on FTD and psychopathology are mediated by eotaxin. In healthy subjects, eotaxin strongly impacts executive functioning and multiple cognitive domains. In schizophrenia, peripheral levels of eotaxin strongly impact both negative symptoms and psychosis (hallucinations and delusions), and these eotaxin effects are mediated by impairments in frontal functioning, memory, sustained attention, and FTD. Eotaxin is an endogenous cognitive deteriorating chemokine (ECDC) and a novel therapeutic target for age-related cognitive decline and schizophrenia as well.

Null Effects on Working Memory and Verbal Fluency Tasks When Applying Anodal tDCS to the Inferior Frontal Gyrus of Healthy Participants

Transcranial direct current stimulation (tDCS) is a technique used to modify cognition by modulating underlying cortical excitability via weak electric current applied through the scalp. Although many studies have reported positive effects with tDCS, a number of recent studies highlight that tDCS effects can be small and difficult to reproduce. This is especially the case when attempting to modulate performance using single applications of tDCS in healthy participants. Possible reasons may be that optimal stimulation parameters have yet to be identified, and that individual variation in cortical activity and/or level of ability confound outcomes. To address these points, we carried out a series of experiments in which we attempted to modulate performance in fluency and working memory probe tasks using stimulation parameters which have been associated with positive outcomes: we targeted the left inferior frontal gyrus (LIFG) and compared performance when applying a 1.5 mA anodal current for 25 min and with sham stimulation. There is evidence that LIFG plays a role in these tasks and previous studies have found positive effects of stimulation. We also compared our experimental group (N = 19–20) with a control group receiving no stimulation (n = 24). More importantly, we also considered effects on subgroups subdivided according to memory span as well as to more direct measures of executive function abilities and motivational levels. We found no systematic effect of stimulation. Our findings are in line with a growing body of evidence that tDCS produces unreliable effects. We acknowledge that our findings speak to the conditions we investigated, and that alternative protocols (e.g., multiple sessions, clinical samples, and different stimulation polarities) may be more effective. We encourage further research to explore optimal conditions for tDCS efficacy, given the potential benefits that this technique poses for understanding and enhancing cognition.

Neuropsychological analysis of auditory verbal hallucinations

Recent neuropsychological studies have distinguished deficits in verbal working memory, verbal memory, and confrontation naming from other neuropsychological domains as specifically related to the severity of auditory verbal hallucinations (AVH) in schizophrenia (Gisselgard et al., 2014; Siddi et al., 2017). To extend this research, it was hypothesized that AVH severity would be related only to measures within the language domain and the test battery was augmented with the [CTOPP2 and COWAT…define?] to more comprehensively define the language processing functions most predictive of AVH. A neuropsychological test battery was administered to a group of adult patients diagnosed with schizophrenia and schizoaffective disorder (N = 30), who continued to experience AVH despite clinical treatment. Multiple regression analyses demonstrated that poorer performance on measures of verbal working memory and verbal immediate memory significantly predicted greater AVH severity. Going beyond the prior studies, it was also shown that greater impairment of semantic fluency and lesser impairment in delayed general memory were also significant predictors of AVH. Intellectual ability and executive functioning, considered as covariates, were not significant predictors and their inclusion in regression analyses did not affect the pattern of results. Lastly, when cognitive predictors were accounted for, a trend toward an effect of medication (assessed as olanzapine equivalents) emerged such that higher dose predicted less severe AVH. Taken together, better performance on measures of linguistic processes associated with verbal working memory, semantic fluency and verbal learning predicts less severe AVH, perhaps most consistent with limited capacity language processing models. The finding that better delayed memory predicted more severe AVH is consistent with AVH memory models suggesting that AVH are dependent upon information recalled from memory storage.

Effects of PER3 clock gene polymorphisms on aging-related changes of the cerebral cortex

Considerable evidence suggests that circadian rhythmicity is progressively disrupted in senescence. Among clock genes, Period3 (PER3) has been associated with circadian phenotypes, homeostatic regulation of sleep, and cognitive performance in young adults. However, the effects of PER3 genotype on aging-related changes in both cognitive function and cortical integrity remain largely unknown. To shed light into this issue, we have investigated differences in cognitive performance, patterns of cortical thickness, and cortical glucose consumption in normal elderly subjects homozygous carriers of the short (PER3^4/4, n = 32) and long repeat alleles (PER3^5/5, n = 32). Relationships between cognitive performance and cortical thickness/metabolism were further explored for each PER3 genotype. We found that PER3^5/5 carriers had poorer cognitive performance (attention, executive function, semantic memory, and verbal fluency) and lower cortical integrity (structural and functional) than PER3^4/4. PER3^5/5 further showed thinning of temporo-parietal areas, and reductions of glucose consumption in fronto-temporo-parietal regions bilaterally. Moreover, PER3^5/5 subjects exhibited significant correlations between decreased glucose metabolism in fronto-parietal regions and poorer cognitive flexibility, though only correlations with lower glucose consumption of the supramarginal gyrus distinguished PER3^5/5 from PER3^4/4 groups. Overall, these findings enhance our understanding on the gene-brain interaction in aging, and may have further implications for the detection of subclinical cognitive decline associated with PER3 genotypes in late life.

Ineffective initiation contributes to deficient verbal and non-verbal fluency in patients with schizophrenia

AIMS

Patients with schizophrenia (SCH) show impaired verbal and non-verbal fluency. However, these individuals' fluctuations in words or designs generation efficiency over time, a phenomenon that may significantly affect fluency, have never been studied. Thus, the aim of this research was to investigate if individuals with SCH may present with alternations in the dynamics of the information production and its control as well as to test if the potential abnormalities in this regard might affect these patients' overall performance on both verbal and non-verbal fluency tasks.

METHOD

Forty-four patients with SCH and 40 healthy controls (HC) completed both verbal (phonological, semantic) and non-verbal fluency tests. To analyse processing efficiency changes over time, the period in which subjects had to generate words or designs (60 s) has been divided into 15-s sections.

RESULTS

In comparison to HCs, individuals with SCH obtained significantly lower total scores for all fluency measures. Furthermore, group differences in the dynamics of the test performance also emerged, with SCH patients having a significantly worse production during the initial 15 s of each fluency task. Additionally, the initial production deficiency seen in patients with SCH has accounted for these individuals' total performance. Moreover, comparisons of errors distribution over time during the phonemic and figural fluency performance also revealed differences, suggesting there was a rapid depletion in maintaining of cognitive control in the SCH sample.

CONCLUSIONS

Inefficient fluency in SCH may arise from a more general initiation deficits that may partly account for these patients' cognitive problems.

The Brazilian standardization of the MATRICS consensus cognitive battery (MCCB): Psychometric study

OBJECTIVE

Translate, adapt, and validate the MATRICS Consensus Cognitive Battery (MCCB) in Brazil.

METHOD

The present study followed three steps: 1) translation to Portuguese, cultural adaptation, and back translation to English; 2) completion of a pilot study (N=30) conducted with the purpose of assessing whether the general comprehension of the items was clear and all participants adequately responded to the battery; 3) completion of a Reliability and Validation Study of the Brazilian version of the MCCB with 99 individuals with schizophrenia and 99 healthy subjects. All participants were administered the Structured Clinical Interview for DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) and patients were also rated on the Global Assessment of Functioning (GAF) Scale and the Positive and Negative Symptoms Scale (PANSS).

RESULTS

The results showed adequate to high levels of baseline and 4-week retest reliability, except the MSCEIT-ME; adequate internal consistency for the MSCEIT-ME for the total sample and patients group, and moderate Alpha for the health control sample; as well as evidence of convergent validity and sensitivity to differentiate performance between the groups. All the 10 MCCB measures showed the lowest learning effects.

CONCLUSION

Overall the Brazilian version of the MCCB showed similar results to the original North American version. Our findings provides reassurance that the MCCB is a reliable and valid measure of cognition across different countries and cultures, which is especially important to the ongoing work in attempting to discover cognition-enhancing drugs and the effects of cognitive interventions for the treatment of schizophrenia.

Neurocognitive performance, psychopathology and social functioning in individuals at high risk for schizophrenia or psychotic bipolar disorder

INTRODUCTION

Although cognitive deficits are consistent endophenotypes of schizophrenia and bipolar disorder, findings in psychotic bipolar disorder (BDP) are inconsistent. In this study we compared adult unaffected first-degree relatives of schizophrenia and BDP patients on cognition, psychopathology, social functioning and quality of life.

METHODS

Sixty-six unaffected first-degree relatives of schizophrenia patients (SUnR), 36 unaffected first-degree relatives of BDP patients (BDPUnR) and 102 controls participated in the study. Between-group differences were examined and Discriminant Function Analysis (DFA) predicted group membership.

RESULTS

Visual memory, control inhibition, working memory, cognitive flexibility and abstract reasoning were linearly impaired in the relatives' groups. Poorer verbal fluency and processing speed were evident only in the SUnR group. The SUnR group had higher depressive and somatization symptoms while the BDPUnR group had higher anxiety and lower social functioning compared with the controls. Individuals with superior cognition were more likely to be classified as controls; those with higher social functioning, prolonged processing speed and lower anxiety were more likely to be classified as SUnR.

LIMITATIONS

The relatives' sample is quite heterogeneous; the effects of genetic or environmental risk-factors were not examined.

CONCLUSIONS

Cognitive functions mediated by a fronto-parietal network, show linear impairments in unaffected relatives of BDP and schizophrenia patients; processing speed and verbal fluency impairments were evident only in schizophrenia relatives. Self-perceived symptomatology and social functioning also differ between schizophrenia and BDP relatives. The continuum seen in patients in several indices was also seen in the cognitive impairments in unaffected relatives of schizophrenia and BDP patients.

Associations of differential schizotypal dimensions with executive working memory: A moderated-mediation analysis

BACKGROUND

Increased schizotypal traits are observed in a percentage of the general population and in the schizophrenia-spectrum and have been associated with impairments in working memory. In this study we examined the effects of four schizotypal dimensions [Negative (NegS), Paranoid (ParS), Cognitive-Perceptual (CPS), Disorganized (DiS)] on executive working memory (EWM), as mediated by set-shifting, planning and control inhibition. We also examined whether these associations are moderated by family-history of psychosis.

METHODS

Our sample consisted of 110 unaffected first-degree relatives of schizophrenia-spectrum patients and 120 control individuals. Schizotypy was assessed with the Schizotypal Personality Questionnaire. Participants were also tested with the Letter-Number Sequencing, Wisconsin Card Sorting, Stroop Color-Word and Stockings of Cambridge tasks. The effects of set-shifting, control inhibition and planning on the relationship between schizotypy and EWM were examined with mediation analyses. Moderated-mediation analyses examined potential moderating effects of group membership (unaffected relative/community participant).

RESULTS

All mediators were significant in the relationship between NegS and EWM. The effects of ParS were mediated only by set-shifting and planning. Planning and control inhibition were the only significant mediators on the effects of CPS and DiS on EWM, respectively. The moderated-mediation analyses revealed that these findings apply only in the community group.

CONCLUSIONS

We found that the effects of different schizotypal dimensions on EWM are mediated by other cognitive processes in individuals without personal/family history of psychosis. This is probably due to either more severe impairments in the cognitive processes of the relatives or restrictions in our sample and study-design.